P0234
Turbocharger/Supercharger "A" Overboost Condition
High· Fix promptlyProfessionalPowertrainGeneric, all makes
What it means
The turbo is producing more boost pressure than it should. Too much boost can damage the engine.
Is it safe to drive?
Drive gently and avoid full throttle. The ECU will usually cut power to protect the engine.
Symptoms
- Check engine light on
- Limp mode
- Surging power
Probable causes
Most likely first
- 1Wastegate stuck closed
- 2Sticking variable geometry turbo (VGT) vanes
- 3Faulty boost control solenoid
- 4Cracked or disconnected wastegate vacuum line
- 5Faulty boost pressure sensor
How to diagnose it
Work through these in order before buying parts
- 1Record the code and its freeze frame data (speed, load, temperature when it set), then clear it and see if it comes back.
- 2Compare desired and actual boost on live data.
- 3Check the wastegate or VGT actuator moves freely.
- 4Check vacuum lines and the boost control solenoid.
- 5Check for technical service bulletins (TSBs) or software updates for your make and model; some codes have known factory fixes.
Common fixes
- Free up or replace the wastegate or VGT actuator
- Replace the boost control solenoid
- Replace damaged vacuum lines
- Replace the boost sensor
This information is general guidance for all makes. Exact causes, specifications and procedures vary by vehicle, so confirm with your service manual or a qualified mechanic before replacing parts.